This is a re-submission of a new application for an Institutional training grant to train pre-and post doctoral fellows at the University of Chicago in research related to O2 Biology in Health & Disease. Rationale: Understanding the mechanisms of O2 sensing and determinants of cellular O2 requirements are fundamental to many disease processes. Recent advances provided a paradigm shift in our understanding of how cells sense O2, and also spectacular insights into the molecular basis for how organisms adapt to changes in O2 environment. The translational potential of O2 biology attracted the attention of researchers in various disciplines of Biology & Medicine and there is an absolute need to provide research training in O2 biology to the next generation of basic and physician scientists. The goals of the program are a) to provide trainees with a broad foundation in the O2 biology in the areas of O2 sensing, O2 Patho-biology, Ischemia-Reperfusion, and Biology of reactive oxygen species and b) to prepare trainees to pursue competitive careers in basic and/or clinical research, teaching in academia and/or the biotechnology field. The proposed faculty members have established research programs in one or more areas of O2 biology and have trained a number of successful scientists. The training faculty represents 5 clinical and 3 basic science departments. This training program is built upon existing collaborations amongst the proposed faculty and fosters training through collaborative research related to O2 biology. We request 2 pre-doctoral and 5 post-doctoral positions. The pre-doctoral trainees will be recruited from one or more of the Ph.D. awarding committees, and Post-doctoral trainees recruWed will include: 1) Ph.D. post-doctoral trainees, 2) MDs recruited in clinical fellowship programs in Medicine, Pediatrics, Surgery, Radiation-oncology, and Anesthesia and 3) MD-Ph.D.s recruited into the Physician-Scientist Development Program in the Department of Medicine. Both pre-and post doctoral trainees will be offered an interdisciplinary course in O2 Biology along with core curriculum, seminars and Journal clubs. In addition to research, training in grants-manship and writing skills will be offered enabling them to become independent scientists. Our proposed training program, which emphasizes crossing of departmental barriers and scientific disciplines, will develop well-rounded scientists trained in O2 biology, which has basic and translational significance.